US blockade on Iranian ports: What it means, its implications

The US Central Command (CENTCOM) had earlier said that its forces will enforce the blockade impartially against vessels of all nations entering or departing Iranian ports and coastal areas, including those “on the Arabian Gulf and Gulf of Oman”, adding that the forces will not impede freedom of navigation for vessels transiting the Strait of Hormuz to and from non-Iranian ports.

What a blockade entails

Former senior naval officers explained that a blockade is an act of war or an International Armed Conflict as it involves an operation by a belligerent state engaged in a conflict to prevent vessels and/or aircraft of all states — enemy as well as neutral — from entering or exiting specified ports, airfields, or coastal areas belonging to, occupied by, or under the control of an enemy belligerent state.

It is for the same reason that the Kennedy administration during the 1962 Cuban Missile Crisis called its naval action a quarantine and not a blockade.

Vice Admiral Pradeep Chauhan (retd) said a blockade typically involves the deployment of surface combatant vessels to stop, inspect and, where appropriate, to seize or capture vessels that are reasonably suspected to be attempting to breach the blockade.

“A blockade may be a ‘close blockade’, in which the blockading force is deployed relatively close to the ports or coastal stretch that are being subject to blockade,” he explained.

However, he added that since such ships will themselves become targets for action by the enemy (the belligerent against whom the blockade is being imposed), the distance at which the blockading force is deployed varies depending upon the assessed range of shore-based weaponry available with the blockaded country.

“This often leads to the imposition of a “distant’ blockade. Obviously, in the case of a distant blockade, ships intending to breach the blockade would have a better chance of simply going around the pattern of deployment of the ships seeking to impose the blockade,” he said.

He added that this is why it is so important for the blockade to be maintained by a force sufficient to truly prevent access to the coasts of the enemy (in other words, the blockade has to be “effective”.

Legal compliance

Vice Admiral Chauhan further explained that for a blockade to be legally compliant, it must fulfil certain criteria, including:

(a) It must be duly established and declared by notification to both, belligerent and neutral states (in other words, it must be instituted under the authority of a belligerent government, and the declaration to this effect must notify the commencement of the blockade. While there is no requirement to provide an end date, whenever it is terminated, the fact of such termination must also be notified.

(b) It must be continuously maintained and impartially enforced against all vessels alike.

(c) It must have a lawful military objective. For instance, it is illegal to impose a blockade whose sole purpose is to starve the civilian population or to deny the civilian population other objects essential for its survival.

(d) It must be ‘effective’, which means that it must be maintained by a force sufficient to truly prevent access to the coasts of the enemy. It is illegal to impose a “paper” blockade, with no intention or possibility of enforcing it.

Former National Maritime Security Coordinator Vice Admiral G. Ashok Kumar (retd) stated that if the blockade is implemented, it will exacerbate the global energy crisis, which began when Iran started blocking the Strait of Hormuz during the US-Israel-Iran conflict.

“Iran, being a littoral, had a strategic advantage in the Persian Gulf region. So, any other forces operating there could be vulnerable to a saturation attack by drones and missiles by Iran, if it so decides,” he explained.

He added that a blockade by a belligerent could also involve confiscating vessels coming to and from the ports of another belligerent nation.

Explaining how the blockade might affect India, Vice Admiral Chauhan explained that it might affect Indian exports to Iran and Indian imports from Iran, not merely oil and natural gas.

“India’s merchandise seaborne trade with Iran in 2025–26 has remained relatively modest (roughly USD 1.1–1.2 billion in April–December 2025). However, it is important for the Indian economy because it is dominated by Indian exports of foodgrains and pharma products,” he said, citing the examples of rice, pharmaceuticals and immunological products, as well as smaller exports such as iron and steel items, machinery and electrical goods, and organic chemicals.

“India’s imports from Iran are presently concentrated in non-crude oil commodities such as petroleum bitumen, methanol/energy-related materials, and construction-linked minerals such as gypsum,” he said.